New porous monolithic membranes based on supported ionic liquid-like phases for oil/water separation and homogenous catalyst immobilisation

Article abstract of DOI:10.1039/c8cc00371h

Porous monolithic advanced functional materials based on supported ionic liquid-like phase (SILLP) systems were used for the preparation of oleophilic and hydrophobic cylindrical membranes and successfully tested as eco-friendly and safe systems for oil/water separation and for the continuous integration of catalytic and separation processes in an aqueous-organic biphasic reaction system.

Full text of DOI:10.1039/c8cc00371h

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New porous monolithic membranes based on Supported Ionic
Liquid-Like Phases for oil/water separation and homogenous
catalyst immobilisation
Received 00th January 20xx,
Accepted 00th January 20xx
Raúl Porcar,a Daniel Nuevo,a Eduardo García-Verdugo,a* Pedro Lozano,b José Sanchez-Marcano,c
M. Isabel Burguetea and Santiago V. Luisa*
DOI: 10.1039/x0xx00000x
www.rsc.org/
Porous monolithic advanced functional materials based on into the corresponding monolith, the mechanical strength of
Supported Ionic Liquid-Like (SILLPs) systems were used for the the membranes was highly dependent on their composition.
preparation of oleophilic and hydrophobic cylindrical membranes Mixtures just containing chloromethyl styrene (ClVB) and
and successfully tested as eco-friendly and safe systems for divinyl benzene (DVB), even when
a large amount of
oil/water separation and for the continuous integration of crosslinking agent was used (entries 1 and 2, Table S-1, ESI),
catalytic and separation processes in an aqueous–organic biphasic showed very low mechanical strength, fracturing by simple
reaction system.
finger tight pressure. However, the inclusion of acrylic
monomers in the monomeric mixture hardened the resulting
membranes, being more resistant to external deformation.
Among the seven compositions assayed, two of them provided
cylindrical membranes with a suitable mechanical strength (M-
Membrane engineering has been recognized as one of the core
technologies in green chemistry and green engineering.1-5 In
the search of new advanced materials for membranes, the so-
called polymeric ionic liquids (PILs) offer new exciting
possibilities as these new materials combine the unique
features of Ionic Liquids (ILs) with those of advanced polymeric
materials.6,7 The presence on the polymeric backbone of the
membrane of ionic liquid-like moieties provides a simple
method to tune the porosity and wettability of the membrane
surface and therefore their performance.8,9 Here we report on
the preparation, characterization and application of new
tubular cylindrical polymeric membranes based on Supported
Ionic Liquid-Like Phases (SILLPs).
1
and M-2, see ESI, entries 6 and 7, Table S-1). Both materials
contained a 13% by weight of functional monomer (ClVB, ca.
0.85 mmol Cl/g), which could be converted into the
corresponding IL-like units by reaction of the M-1 and M-2
with neat methyl or butyl-imidazole (see ESI, Scheme S-1) to
provide membranes M-1-SILLP-Cl and M-2-SILLP-Cl (a for
for butyl imidazolium moieties).19,20
methyl imidazolium and
b
The membranes could also be further modified by exchanging
-
the Cl- anion by NTf2 to achieve membranes M-1-SILLP-NTf2
and M-2-SILLP-NTf2
.
The success of the successive
Porous polymer monoliths offer distinct advantages for
technological applications over other polymeric materials,
which have been exploited in separation and catalysis.10-18 The
synthesis of the desired porous monolithic tubular membranes
was carried out by bulk polymerization of the corresponding
monomeric mixture in the presence of an adequate porogenic
agent using a mould with a hollow cylindrical shape (see ESI,
Fig. S-1). Different monomeric mixtures were evaluated for
this purpose (see ESI, Table S-1). Although all the
polymerization mixtures gave full conversion of the monomers
modifications was assessed by FT-ATR-IR, NBP-test and
elemental analysis (see ESI, Fig. S-2 and S-3 and Table S-2 and
S-3).20,21
The morphological and physicochemical properties of the
membranes are summarized in Fig. 1. Both the SEM and Hg
porosity data demonstrated that the membranes presented
open porosity (see ESI, Fig. S-4 and Table S-3). Noteworthy,
upon the introduction of the IL-like units, the porosity of the
membrane M-1 significantly changed. The unmodified
membrane presented a medium pore diameter of 21 nm with
ca. 32% open porosity. The introduction of methyl imidazolium
or butyl imidazolium units induced an increase on both pore
size and open porosity (36 nm mean open diameter –MPD- for
M-1-SILLP-Cl-b with an open porosity of ca. 37%). The
exchange of Cl- by NTf2 also induced a further change on the
-
pore structure. Thus, M-1-SILLP-NTf2-b displayed a slight
reduction in the mean pore size (32 nm MPD) which was
associated with an increase in the measured open porosity (ca.
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40%) relative to the parameters obtained for M-1-SILLP-Cl-b
.
bulkier groups. These structural differences are reflected on
However, in contrast to the observations in M-1 derived the morphological differences and in the separation behaviour
membranes, the modification of M-2 did not induce any (vide infra).
significant impact on the open porosity providing membranes Macroscopic properties of these porous monolithic tubular
with an open porosity of ca. 36 % in all instances, while the membranes could be tailored through the proper selection of
pore size decreased upon modification, achieving MPD values monomeric composition and the postmodification with
ranging from 44 nm to 32 nm, in good agreement with the different IL-like fragments. This can be illustrated by the
changes in the sizes of the imidazolium and the counter-ion observed changes in the hydrophilicity of the surface for the
fragments introduced upon modification.
considered membranes (see data in Fig. 1). Thus, for the initial
membrane M-1, the measured WCA was 43.7o, which is
reasonable for
a relatively hydrophobic material. The
introduction of methyl imidazolium chloride units rendered a
hydrophilic material, where water was fully absorbed. When
butyl imidazolium chloride moieties were introduced instead,
the hydrophilicity of the membrane slightly decreased as
shown by the value of the Water Contact Angle (WCA, 24.8o).
The change of the hydrophilic chloride anion by a more
-
hydrophobic one (NTf2 ) increased again the hydrophobic
character of the material (WCA 51.8o). Interestingly, in the
case of M-2 the macroporous character and the large pore size
allowed the full absorption of the water droplets in spite of its
composition being relatively similar to that of M-1. In this case,
the same behaviour was observed for the membranes
obtained through the introduction of methyl or butyl
imidazolium chloride fragments. However, the introduction of
the bulkier and more hydrophobic (anion and cation
Fig 1 Main properties of the membranes considered in this work. M-1 and M-2 combination) butyl imidazolium bistriflamide (M-2-SILLP-NTf2-
) rendered a highly hydrophobic membrane (WCA 100o).
contain chloromethyl groups instead of the corresponding imidazolium fragments.
b
WCA: Water Contact Angle; MPD: Mean Pore Diameter
The potential of these membranes for different applications
was tested with the help of two proof-of-concept experiments.
Our initial studies were concentrated on the efficient
separation of oil−water (O/W) mixtures under ultrafiltration
The SEM pictures presented in Fig. S-4a confirm the presence
of a larger pore structure for M-2 than for M-1. The membrane
M-2 exhibits a more uniform polymer pore particle size, a
relatively narrower pore size distribution and a larger surface
area than M-1. This effect is even more significant when the
pictures for the inside and outside surfaces of the membranes
are compared. The SEM pictures of the modified M-2
membranes (see ESI, Fig. S-4b) also confirmed the pore size
diminution obtained by the introduction of the IL-like units.
The differences between these two families of membranes can
be related with the absence of DVB in the monomeric mixture
(UF) conditions, where the use of membranes offer
a
prospective solution for the problem of micron sized oily
wastewater separation.23,24,25 As a model system, two mixtures
of n-hexane/water: 1:1 as a dispersed oil (74 ± 4 µm oil-
droplet) and 95:5 as an emulsion (31.3 ± 1.9 µm oil-droplet)
were evaluated. Fig. ESI-5 depicts the schematic
representation of the set-up used for this study. Both
unmodified monolithic tubular membranes (M-1 and M-2
)
were tested for separation of these O/W mixtures and the
results compared with those obtained for the more
hydrophobic membranes containing IL-like fragments (M-1-
SILLP-NTf2-b and M-2-SILLP-NTf2-b) under a pressure of 6.5 ±
0.5 bar and three different tangential flows (0.3, 0.6 and 1.2
L·h-1). An excellent separation of the n-hexane was achieved
(selectivity on the permeate > 99% of n-hexane) for both
dispersed and emulsioned O/W mixtures. For the dispersed
O/W n-hexane/water (1/1) mixture, differences on
performance between the modified and unmodified
membranes were observed at the lower tangential flows of 0.3
and 0.6 L·h-1. The SILLP-derived membranes provided better
permeability than the unmodified membranes (see ESI, Fig. S-
6). Thus, for instance, at a tangential flow of 0.3 L·h-1, the
permeate flow was 23.5 and 27.6 L·m-2·h-1 for M-1-SILLP-NTf2-
for M-1. The styrenic monomers can generate gel-type
domains,10,12 which can be significantly affected by the
presence of the different imidazolium fragments, taking into
account their potential to establish additional strong
crosslinking interactions of polar and ionic character.9,20,22 The
presence of these gel-type domains was confirmed by the
swelling behaviour observed for M-1 derived membranes in
the presence of suitable solvents, in particular methyl butyl
imidazole and n-hexane. The introduction of the additional
DVB crosslinking agent in the membrane M-2 can induce a
transition from the styrenic gel-type domains to a pure
macroporous structure with a well-defined permanent porous
domain independent of the solvent used.10,12 This overall
macroporous structure should be less affected by modification
of the functional units, but would provide a decrease in the
observed mean porous diameter upon introduction of the
b
and M-2-SILLP-NTf2-b, in comparison with the values of 7.0
and 15.2 L·m-2·h-1 obtained from the unmodified membranes
2 | J. Name., 2012, 00, 1-3
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M-1 and M-2. These results indicated a clear positive effect of and the reactive emulsion was recirculated at a tangential flow
the presence of the IL-like units on the overall performance of of 0.3 L·h-1.
these membranes. As could be expected, an experiment with Under these conditions and applying a back-pressure of 5 bar,
the membrane M-2-SILLP-NTf2-b confirmed how it was also a permeate flow of 2 L·h-1·m-2 was initially achieved for M-2-
able to efficiently separate a similar dispersion of gasoline in SILLP-NTf2-b (see ESI, Fig. S-9). The analysis of the permeate
water with a permeate flow of 21.9 L·m-2·h-1.
obtained revealed that it did not contain traces of water and a
Regarding the emulsioned n-hexane/water (95:5) mixture, the concentration of the product of 190 g·L-1, corresponding with a
membrane M-1-SILLP-NTf2-b displayed a significantly better yield of ca. 80% yield and a mass flow of 381 g·h-1·m-2. As in
performance than the other membranes tested (see ESI, Fig. S- this process 2-Me-THF was continuously extracted, the content
7). For M-1-SILLP-NTf2-b, the larger permeate flow obtained in organic phase of the mixture fed to the membrane
was 6.5 L·m-2·h-1 when using a tangential flow of 0.3 L·h-1. This decreased with the time, leading to a concomitant reduction
permeate flow was 10 times larger than the one found for the of the permeate volumetric and mass flow rate as can be
unmodified membrane under identical experimental observed in the data presented in Fig. S-9 (ESI). However, no
conditions. This suggests that the gel domains defined in the reduction in yield was detected in the permeate obtained at
M-1-SILLP-NTf2-b membrane are swelled by the organic different times. Additionally, the membrane M-1-SILLP-
component in the presence of the emulsion, favouring its NTf2-b was also tested under the same conditions. Although
permeation through the membrane, while the hydrophobic the difuryl compound was isolated in high yield (89% yield),
swollen gel domains fill the open porous structure precluding this system showed a slightly lower performance with a mass
the access of water, allowing in this way for an efficient flow of 238 g·h-1·m-2 and a permeate flow of 0.56 L·h-1·m-2.
separation of the emulsion. This permeation mechanism is not
available in the macroporous M-2-SILLP-NTf2-b where the
emulsion can occlude the pore inhibiting the flow through the
membrane by dynamic flow.
Based on this efficient separation of oil/water mixtures, an
evaluation of the capacity of these IL-like-based membranes
for developing systems combining reaction and separation
processes was carried out. Furfural (
base-catalysed aldol condensation reactions with carbonyl
compounds to produce mono- or difuryl compounds like , of
3) is known to undergo
4
interest in different fields including their use for biomass
derived fuels.26 Mineral and solid bases have been the
traditional catalysts for this reaction. However, this method
still has some shortcomings as, traditionally, a high dosage of
catalyst (>30 mol %) has to be used to obtain the double
condensation to difuryl components. Besides, a long reaction
time is required to achieve a reasonable condensation yield
and separation processes, including the separation and reuse
of the homogeneous catalysts from the reaction mixture,
represent an important bottleneck for practical application. In
Fig
separation of difuryl compound
2 Experimental set-up for the integrated continuous synthesis and
4
an initial test, membranes M-1-SILLP-NTf2-b and M-2-SILLP- In the light of these results, the reaction/separation was then
NTf2-b were able to separate a 1:1 dispersion of 2-Me-THF in assayed under continuous flow conditions. The reaction
water. In this regard, a biphasic 2-Me-THF/water system can mixture was recirculated with a tangential flow of 0.3 L·h-1 and
provide
a suitable medium for the synthesis of 4 by at a pressure of 5 bar to obtain a constant flow of permeate,
establishing an appropriate contact of a solution of furfural while the reactor tank was continuously fed with fresh solution
and acetone in 2-Me-THF with a catalytic NaOH aqueous of furfural/acetone in 2-Me-THF at the same flow than that of
solution. The low solubility of the product (4) in water and the the permeate (Fig. 2). Under these conditions, the integrated
selective permeation of the 2-Me-THF phase should favour the continuous separation/reaction was efficiently carried out for
integration of reaction and separation processes, allowing a at least 20 hours (see ESI, Fig. S-10). The flow rate of the
simple separation of the organic phase and the continuous permeate across the SILLPs-based membrane was slightly
reuse of the aqueous catalytic phase (Fig. 2). The biphasic reduced during this time from 1.1 to 0.8 L·h−1·m−2, which could
reaction was firstly evaluated under batch conditions and the be related to the fouling of the membrane by short oligomers
two different phases were separated and analysed at different produced during the condensation. All permeate fractions
time intervals (see ESI, Fig. S-8). The condensation took place showed a very good yield for the difuryl aldol product (4, yield
in relatively short times showing, after 60 min, yields of ca. > 90%) achieving a mean permeate mass flow of 208 g·h-1·m-2.
90% for both phases. Once demonstrated the efficiency of the These initial results demonstrate the suitability of membrane
reaction under these biphasic conditions, the membrane reactor technologies based on the use of IL-like-based
module was attached to the reaction system (see ESI, Fig. S-5a) polymeric materials (SILLPs). These new materials bring
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23 R. M. Padaki, S. Murali, M. S. Abdullah, N. Misdan, A.
Moslehyani, M. A. Kassim, N. Hilal and A. F. Ismail,
Desalination, 2015, 357, 197-207.
together the unique properties of the ILs and the ones of
porous monolithic advanced functional polymers, opening new
avenues for the development of greener and more efficient
chemical processes. The modular character of IL-related
fragments allows the fine-tuning of SILLPs in developing
materials for advanced applications.
24 C.-X. Cao, J. Yuan, J.-P. Cheng and B.-H. Han, Sci. Reports,
2017,
25 W. C. Wan, Y. H. Lin, A. Prakash and Y. Zhou, J. Mat. Chem. A,
2016, , 16687-18705.
7, 3101.
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26 S. Shylesh, A. A. Gokhale, C. R. Ho and A. T. Bell, Acc. Chem.
Res., 2017, 50, 2589-2597.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
Financial support from MINECO (CTQ2015-68429-R and CTQ-
2015-7927), Generalitat Valenciana (PROMETEO/2016/071)
and Comunidad Autónoma de la Región de Murcia (CARM
Seneca 18278/PI/14) is acknowledged. The technical support
from the SCIC of the UJI is also acknowledged.
Notes and references
1
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Hovorka and P. J. Dyson, ChemPlusChem, 2018, 83, 7-18.
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E. García-Verdugo and S. V. Luis, J. Mater. Chem. A, 2017, 5,
9733-9744.
10 E. C. Peters, F. Svec and J. M. J. Frechet, Adv. Mater., 1999,
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11 B. Altava, M. I. Burguete, E. Garcia-Verdugo, S. V. Luis, M. J.
Vicent and J. A. Mayoral, React. Funct. Polym., 2001, 48, 25-
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and V. Sans, Green Chem., 2008, 10, 401-407.
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4 | J. Name., 2012, 00, 1-3
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New porous monolithic membranes based on Supported Ionic Liquid-Like Phases
for oil/water separation and homogenous catalyst immobilisation
Raúl Porcar,a Daniel Nuevo,a Eduardo García-Verdugo,a* Pedro Lozano,b José Sanchez-Marcano,c M. Isabel Burguetea and
Santiago V. Luisa*
a.
Dpt. of Inorganic and Organic Chemistry, Supramolecular and Sustainable Chemistry Group, University
Jaume I, Avda Sos Baynat s/n, E-12071-Castellón. Spain.
b.
Dpt. of Biochemistry and Molecular Biology “B” and Immunology, Faculty of Chemistry. University of
Murcia, Campus de Espinardo. P.O. Box 4021. E-30100- Murcia. Spain.
c.
Institut Européen des Membranes (IEM), Université de Montpellier - Case courrier 047, 2 Place Eugène
Bataillon 34095 Montpellier cedex 5, France.
TABLE OF CONTENTS GRAPHICS
Membranes based on Supported Ionic Liquid-Like systems (SIILPs) with tuneable properties allowed oil/water
separation and reaction/separation integration in biphasic systems

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DOI: 10.1039/C8CC00371H
New porous monolithic membranes based on Supported Ionic Liquid-
Like Phases for oil/water separation and homogenous catalyst
immobilisation
Raúl Porcar,a Daniel Nuevo,a Eduardo García-Verdugo,a* Pedro Lozano,b José Sanchez-
Marcano,c M. Isabel Burguetea and Santiago V. Luisa*
a.
Dpt. of Inorganic and Organic Chemistry, Supramolecular and Sustainable
Chemistry Group, University Jaume I, Avda Sos Baynat s/n, E-12071-Castellón. Spain.
b.
Dpt. of Biochemistry and Molecular Biology “B” and Immunology, Faculty of
Chemistry. University of Murcia, Campus de Espinardo. P.O. Box 4021. E-30100- Murcia.
Spain.
c.
Institut Européen des Membranes (IEM), Université de Montpellier - Case courrier
047, 2 Place Eugène Bataillon 34095 Montpellier cedex 5, France.
Supporting information
1. Schemes, Figures and Tables:
Scheme S-1 Synthesis of the SILLPs-based membranes
Fig. S-1 Schematic representation of the method used for the preparation of the polymeric
membranes
Fig. S-2 FT-IR-ATR spectra of the materials obtained by chemical modification of M-1
and M-2 according to Scheme S-1
Fig. S-3 Illustration of the results of the NBP-test for the different synthetic steps involved
in the preparation of the membranes M-(1-2)-SILLP-Cl-(a-b)
Fig. S-4 SEM images for membranes M-1, M-2, M-2-SILLP-Cl-b and M-2-SILLP-
NTf2-b.
Fig. S-5 a) Picture of the set-up used for the biphasic aldol condensation of furfural with
acetone under flow conditions and continuous membrane separation. b) Schematic
representation of the system used for O/W separation
Fig. S-6 Results obtained for the O/W separation of a dispersed mixture of n-
hexane/water (1:1)
Fig. S-7 Results obtained for the O/W separation of an emulsioned mixture of n-
hexane/water (95:5)
1

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Fig. S-8 Kinetic analysis of the biphasic aldol condensation of furfural with acDeOtoI:n10e.1i0n39a/C8CC00371H
2-Me-THF:water (1:1) mixture under batch conditions
Fig. S-9 Results for the integration of reaction and separation of the biphasic aldol
condensation of furfural with acetone in a 2-Me-THF:water (1:1) mixture under batch
conditions using the M-2-SILLP-NTf2-b membrane
Fig. S-10 Results for the integration of reaction and separation of the biphasic aldol
condensation of furfural with acetone in a 2-Me-THF:water (1:1) mixture under
continuous flow mode, using the M-2-SILLP-NTf2-b membrane
Table S-1 Polymerization mixtures tested for the preparation of tubular membranes
Table S-2 Loading of IL-like units based on Elemental Analysis
Table S-3 Main physico-chemical properties of the different porous monolithic tubular
membranes considered in this work
2. General experimental procedures
3. Synthesis of the tubular membranes by bulk polymerization
4. Oil/water separation
5. Study of the kinetics of the aldol condensation of furfural with acetone in batch
mode
6. Evaluation of the integration of reaction and separation in the aldol condensation
of furfural with acetone under flow conditions in batch mode
7. Evaluation of the integration of reaction and separation in the aldol condensation
of furfural with acetone under flow conditions in the continuous flow mode
9. Characterization of (1E,4E)-1,5-di(furan-2-yl)penta-1,4-dien-3-one
10. NMR Spectra
11. References
2

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Scheme S-1 Synthesis of the SILLPs-based membranes
3

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Fig. S-1 Schematic representation of the method used for the preparation of the polymeric
membranes. a) Set-up of the mould used for the preparation of the membranes: The outer
cylinder was a 15 x 1 cm Omnifit® glass column and the inner cylinder was 0.6 cm
diameter glass bar located concentrically to the Omnifit® column using Omnifit®
connectors. b) Photograph of the mould once assembled. c) Photograph of one of the
membranes after demoulding. d) Visual comparison between a commercial ceramic
membrane and one of the prepared polymeric membranes
Experimental procedure:
1.
2.
Addition of the polymerisation mixture to the mould
60-70ºC, 24 h
Removal of the glass pieces of the mould
1 Addition polymerization mixture
3.
2. 70 oC, 24 hours
4.
Washing and drying
3. Remove from the mold
4. Washing draying
c)
b)
Mould
Mold
a)
polymeric
ceramic
Polymerisation
mixture
d)
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Fig. S-2 FT-IR-ATR spectra of the materials obtained by chemical modification of M-1
and M-2 according to Scheme S-1. Arrows indicate the main changes observed associated
to the expected transformations
100
80
60
40
20
125
120
M-1
M-2
110
100
90
M-1-SILLP-Cl-a
M-1-SILLP-Cl-b
M-2-SILLP-Cl-a
M-2-SILLP-Cl-b
%T
%T
CH2-Cl group
1265 cm-1
670 cm-1
CH2-Cl group
1265 cm-1
670 cm-1
80
76
1800
1800
1600
1400
1200
1000
800
600
1600
1400
1200
1000
800
600
Wavenumber [cm-1]
Wavenumber [cm-1]
100
90
80
70
60
50
100
90
80
70
60
M-1-SILLP-Cl-b
M-2-SILLP-Cl-b
%T
%T
M-1-SILLP-NTf2-b
M-2-SILLP-NTf2-b
SO2-NH group
1370-1330 cm-1
1180-1120 cm-1
SO2-NH group
1370-1330 cm-1
1180-1120 cm-1
C-F group
1050 cm-1
C-F group
1050 cm-1
1800
1600
1400
1200
1000
800
600
1800
1600
1400
1200
1000
800
600
Wavenumber [cm-1]
Wavenumber [cm-1]
5

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Fig. S-3 Illustration of the results of the NBP-test for the different synthetic steps involved
in the preparation of the membranes M-(1-2)-SILLP-Cl-(a-b). Violet = (+) test (presence
of chloromethyl groups), non-coloured = (−) test (absence of chloromethyl groups). The
initial membranes M-1 and M-2 gave a clear positive NBP-test. Membranes M-(1-2)-
SILLP-Cl- (a-b) all gave negative NBP tests indicating the full substitution of the CH2-
Cl groups for the corresponding imidazolium chloride salt
•
NBP Test
Blue-Violet
Negative NBP Test
Positive NBP Test
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Fig. S-4a SEM images for membranes M-1 and M-2
M-2
Section
M-1
Outside
Outside
Section
Inside
Inside
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Fig. S-4b SEM images obtained for M-2, M-2-SILLP-Cl-b and M-2-SILLP-NTf2-b.
M-2
M-2-SILLP-Cl-b
M-2-SILLP-NTf2-b
Section
Outside
Inside
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Fig. S-5 a) Picture of the set-up used for the biphasic aldol condensation of furfural with
acetone under flow conditions and continuous membrane separation. b) Schematic
representation of the system used for O/W separation
a) Picture of the reactor set-up
Membrane set-up
Pressure
Flow-out
Monitor
Pumps
Permeate
Flow-in
Back Pressure
Stiiring Tank
valve
b) Schematic representation of the ultrafiltration system for the O/W separation
Pressure regulator
Filtration Unit
oil
Permeate
Water
dispersed or emulsioned
O/W.
H2O with dye .
1200 rpm stir.
Pressure sensor
Pump
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Fig. S-6 Results obtained for the O/W separation of a dispersed mixture of n-
hexane/water (1:1)
30
25
20
15
10
5
M-1
M-2
M-1-SILLP-NTf2-b
M-2-SILLP-NTf2-b
0
0,2
0,4
0.4
0.4
0,6
0.6
0,8
1,0
1,2
1.2
0.2
0.8
0.8
1.0
1.0
0.6
1.2
0.2
Tangential flow (L·h-1)
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Fig. S-7 Results obtained for the O/W separation of an emulsioned mixture of n-
hexane/water (95:5)
7
6
5
4
3
2
1
0
M-1
M-2
M-1-SILLP-NTf2-b
M-2-SILLP-NTf2-b
0,2
0.2
0,4
0.4
0,6
0.6
0,8
0.8
1,0
1.0
1,2
1.2
Tangential flow (L·h-1)
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Fig. S-8 Kinetic analysis of the biphasic aldol condensation of furfural with acetone in a
2-Me-THF:water (1:1) mixture under batch conditions. Yields calculated by 1H-NMR.
Triangles: Yield (%) found in the aqueous phase. Circles: Yield (%) found in the 2-Me-
THF phase
100
80
60
40
20
0
0
20 40 60 80 100 120 140 160 180 200
time (min)
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Fig. S-9 Results for the integration of reaction and separation of the biphasic aldol
condensation of furfural with acetone in a 2-Me-THF:water (1:1) mixture undeDrObI:a1t0c.1h039/C8CC00371H
conditions using the M-2-SILLP-NTf2-b membrane. Yields calculated by 1H-NMR.
Red dots represent the permeate mass flow, while the bars correspond to the permeate
volumetric flow
Yield (%): 77
400
80
89
90
350
300
250
200
150
100
50
2
1
0
0
2
3
4
5
time (h)
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Fig. S-10 Results for the integration of reaction and separation of the biphasic aldol
condensation of furfural with acetone in a 2-Me-THF:water (1:1) mixture under
continuous flow mode, using the M-2-SILLP-NTf2-b membrane. Yields calculated by
1H-NMR. Red dots represent the permeate mass flow, while the bars correspond to the
permeate volumetric flow
Yield (%): 82 91 93 96 97 98 97 98 98
2
350
300
250
200
1
150
100
50
0
0
4
6
8
10 12 14 16 18 20 22
time (h)
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Table S-1 Polymerization mixtures tested for the preparation of tubular membranesa,b
ClVB MMA EGDMA VB DVB Mon. Por. Dod. Tol.
Entry
M.S.h
(%)d
(%)d
(%)d
(%)d (%)d (%)e (%)f (%)g (%)g
30
10
40
40
40
13
13
70
90
40
40
40
40
40
70
70
60
60
60
60
60
30
30
75
75
75
25
25
25
10
(-)
(-)
1
2
3
4
30
30
30
30
30
30
30
30
30
30
(±)
(±)
(+)
(+)
(+)
90
100
100
100
5
6 (M1)c
7 (M2)c
27
22
b
-
5
-
-
a
All percentages are given as weight percent. The polymerization was kept at 70ºC for 24h, unless
otherwise stated, and the mixture of polymerization contained 1% in weight of AIBN over monomers. c.
60ºC for 24h; at 70ºC these membranes presented a lower porosity and were relatively fragile. d Percentage
e
of each monomer in the monomeric mixture. Percentage of monomers in the polymerisation mixture
f
(monomers + porogens). Overall percenatage of porogens in the polymerisation mixture (100 - %
monomers). g Percentage of each porogen in the porogenic mixture; Dod.: dodecanol; Tol.: toluene. h M.S.:
mechanical strength = (-) very week, (±) middle , (+) strong
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Table S-2 Loading of IL-like units based on Elemental Analysis
Experimental loading Theoretical loading of
Entry
Membrane
of IL-like units (mmol
IL-like units (mmol
IL/g)
IL/g)a
0.77
0.82
1
2
3
4
M-1-SILLP-Cl-a
M-1-SILLP-NTf2-b
M-2-SILLP-Cl-a
0.85
0.82
0.83
0.79
0.82
0.79
M-2-SILLP- NTf2-b
a According to the composition of the monomeric mixture.
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Table S-3 Main physico-chemical properties of the different porous monolithic tubular membranes considered in this work
Surface Tension. CA (°)
2-Me-TFH
BET Surface
Median Pore Diameter
Total Intrusion
Volume (mL/g)b
0.3833
Entry
Membrane
Porosity b
Area (m2/g)a
(Volume)(nm)b
21.0
Water
Hexane
1
2
3
4
5
6
7
8
M-1
39.42
31.41%
36.79%
37.43%
40.01%
36.05%
35.61%
36.32%
36.45%
43.66
-
-
-
-
-
-
-
-
-
M-1-SILLP-Cl-a
M-1-SILLP-Cl-b
M-1-SILLP-NTf2-b
M-2
-
27.3
0.4730
-
-.
-
-
36.3
0.4968
24.86
-
32.5
0.5003
51.79
-
36.40
44.5
0.4671
-
-
M-2-SILLP-Cl-a
M-2-SILLP-Cl-b
M-2-SILLP-NTf2-b
-
-
-
42.1
0.4649
-
-
-
35.0
0.4584
-
32.1
0.4492
99.78
-
a The test was made with the use of argon. b Mercury Intrusion Porosimetry.
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2. General experimental procedures
All reagents were purchased from Sigma-Aldrich. Furfural was purified by distillation
under reduced pressure. 1H-NMR experiments were obtained using a Bruker Avance III
HD 300 MHz (1H, 300 MHz) spectrometer. The chemical shifts are given in delta (δ,
ppm) values and the coupling constants (J) in Hertz (Hz).
FTIR spectra were recorded on a JASCO 4000 spectrometer equipped with a PIKE ATR
MIRacle accessory. Elemental analyses were performed on an Elemental Carlo Erba 1108
apparatus. Thermal analyses were carried out using a TG-STDA Mettler Toledo model
TGA/SDTA851e/LF/1600 analyser under a flow of N2.
3. Synthesis of porous monolithic tubular membranes: The monomeric mixture, which
was composed for at least a functional monomer and a cross-linking monomer, and the
porogenic agents were weighed according the polymeric composition (see Table S-1 for
each porous polymeric membrane). The resulting homogeneous solution was purged with
N2 during 15 minutes and after that 1% of AIBN was added. The solution was stirred and
sonicated for 15 minutes and poured into a mould (see Fig. S-1). The mould was sealed
and introduced in an oven at 60ºC (or 70ºC) for 24 h. After this time, the porous
monolithic tubular membranes were demoulded and washed for 24 h with methanol to
eliminate the porogens. Finally, the polymeric membranes were vacuum dried at 60oC
until constant weight.
Synthesis of SILLPs-based M-1(2)-SILLP-Cl-a(b) membranes: The porous
monolithic tubular membrane (M-1 or M-2) was submerged in the corresponding neat
imidazole (methyl or butyl imidazole) for 24 h at 80ºC. After this period of time, the
modified porous monolithic tubular membrane was washed with methanol to eliminate
the excess of imidazole for 24 h and then finally vacuum dried at 60oC until constant
weight.
Synthesis of SILLPs-based M-1(2)-SILLP-NTf2-a(b) membranes The former
modified porous monolithic tubular membranes containing imidazolium chloride
fragments were immersed in 150 mL of a solution of 5 equivalents of LiNTf2 in
H2O:MeOH (1:3 v:v) for 24 h under stirring. After this period of time, the corresponding
membrane was washed with methanol for 24 h and then finally vacuum dried at 60oC
until constant weight.
These synthetic protocols had been previously optimized by our group and described in
detail, allowing a quantitative transformation of the chloromethylated fragments into
alkyl benzyl imidazolium groups.1 The resulting materials were characterized by different
techniques, such as FT-IR (Fig. ESI-2)2 and the NBP test (Fig ESI-3,3 which is able to
easily determine the presence of reactive chloromethyl groups and confirmed their
expected structures and the full conversion of the chloromethyl groups into the
corresponding supported imidazolium salts for all the polymeric membraned prepared.
4. Oil/water separation
Oil/water separation experiments were conducted with a membrane filtration system that
can be operated in cross-filtration flow mode (Fig. S-5). The system included a feed tank,
a feed pump, a feed flow meter, a feed pressure gauge, a membrane module, a back
pressure regulator, and a permeate tank.
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The feed tank was loaded with 60 mL of the O/W mixture (1/1 v/v dispersion of n-
hexane/water, 74 ± 4 µm droplet size or a 95/5 v/v emulsion of n-hexane/water, 31.3 ±
1.9 µm droplet size) and then maintained under magnetic stirring (1200 rpm) and pumped
through the filtration module at different recirculation tangential flows (0.3, 0.6 and 1.2
L·h-1) at 6 ± 1 bar back-pressure, obtaining a yellow steady permeate flow, which was
collected at fixed time intervals to determinate its composition and the permeate flow.
5. Study of the kinetics of the aldol condensation of furfural with acetone in batch
mode
The aldol condensation of furfural with acetone was carried out using six different
emulsions of furfural (3, 3.8 g, 0.04 moles), acetone (1.16 g, 0.02 moles) and NaOH (0.34
g, 0.008 moles) in 2-MeTHF (15 mL)/distilled H2O (15 mL). These emulsions were
stirred in an orbital stirrer at 500 rpm and rt, stopped at different times and the phases
separated. The organic phase (2-MeTHF) was concentrated under reduced pressure and
the crude obtained analysed by 1H-NMR. The aqueous phase was extracted with 5 mL of
CHCl3, dried with anhydrous MgSO4 and concentrated under reduced pressure to be
analysed by 1H-NMR. The results obtained are summarised in Fig. S-8.
6. Evaluation of the integration of reaction and separation in the aldol condensation
of furfural with acetone under flow conditions in batch mode
The reactor system consisted of a stirred tank (250-mL total capacity) connected through
a HPLC pump with the ultrafiltration module, containing a cylindrical tubular SILLPs-
based membrane (5.3 cm length, 1 cm e.d. and 0.6 cm i.d., 9.99 cm2 filtration surface
area) (see Fig. S-5a). Firstly, the reactor tank was loaded with 15 mL of a solution of
furfural/acetone in 2-Me-THF (253 mg/mL furfural and 176 mg/mL acetone) and 15 mL
of aqueous NaOH (22.7 mg/mL). Both solutions were emulsioned under high magnetic
stirring (1200 rpm, 150 ± 8 µm droplet size) until a homogeneous suspension was
observed. Then, the pumping was started applying a 5 mL min−1 recirculation flow rate
through the membrane module at 5 ± 1 bar back-pressure, obtaining a slightly yellow and
clear permeate, which was collected at fixed time intervals. The 2-Me-THF in the
permeate samples was removed under vacuum and the resulting product weighted and
analyzed by NMR (1H-NMR in CDCl3). All experiments were carried out in duplicate.
The results are summarized in Fig. S-9.
7. Evaluation of the integration of reaction and separation in the aldol condensation
of furfural with acetone under flow conditions in the continuous flow mode
The reactor system consisted of a stirred tank (250-mL total capacity) connected through
a HPLC pump with the ultrafiltration module, containing a cylindrical tubular SILLPs-
based membrane (5.3 cm length, 1 cm e.d. and 0.6 cm i.d., 9.99 cm2 filtration surface
area) (see Fig. S-5a). Firstly, the reactor tank was loaded with 15 mL of a solution of
furfural/acetone in 2-Me-THF (253 mg/mL furfural and 176 mg/mL acetone) and 15 mL
of aqueous NaOH (22.7 mg/mL). Both solutions were dispersed under high magnetic
stirring (1200 rpm, 150 ± 8 µm droplet size) until a homogeneous suspension was
observed. Then, the pumping was started applying a 5 mL min−1 recirculation flow rate
through the membrane module and at 5 ± 1 bar back-pressure, obtaining a slightly yellow
and clear permeate, which was collected at fixed time intervals. The reactor tank was
continuously fed with fresh furfural/acetone in 2-Me-THF solution at the same flow than
the one for the permetate. The 2-Me-THF of the permeate samples, obtained at regular
time intervals, was removed under vacuum and the resulting product weighted and
19

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analyzed by NMR ( H-NMR in CDCl3). All experiments were carried out in duplicate.
The results are summarized in Fig. S-10.
9. Characterization of (1E,4E)-1,5-di(furan-2-yl)penta-1,4-dien-3-one
(1E,4E)-1,5-di(furan-2-yl)penta-1,4-dien-3-one was obtained as a yellow solid.
1H-NMR (CDCl3, 300 MHz): δ 7.51 (d, J = 2.0 Hz, 2H), 7.45 (s, 2H), 6.91 (d, J = 15.6
Hz, 2H), 6.68 (dd, J = 3.3, 0.6 Hz, 2H), 6.50 (dd, J = 3.4, 1.8 Hz, 2H) ppm.4,1
10. NMR Spectra
1H-NMR (CDCl3, 300 MHz) of a collected fraction of the permeate in 2-MeTHF at 20 h of reaction
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1H-NMR (CDCl3, 300 MHz)of (1E,4E)-1,5-di(furan-2-yl)penta-1,4-dien-3-one
11. References.
1 M. I. Burguete, H. Erythropel, E. Garcia-Verdugo, S. V. Luis and V. Sans, Green
Chem., 2008, 10, 401.
2 For the use of FT-IR and FT-Raman techniques to monitor the progress of the reaction
and for the characterization of the polymers see: B. Altava, M. I. Burguete, E. Garcia-
Verdugo, S. V. Luis and M. J. Vicent, Tetrahedron, 2001, 57, 8675.
3 NBP test: F. Galindo, B. Altava, M. I. Burguete, R. Gavara and S. V. Luis, J. Comb.
Chem., 2004, 6, 859.
4 M. Gu, Q. Xia, X. Liu, Y. Guo and Y. Wang, ChemSusChem, 2017, 10, 4102.
21